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My Categorization Free-Viewing Displays SIRDS Stereo Pairs Barrier-Strip Lenticular Aided-Viewing Displays Anaglyph Polarized Field-Sequential Tradeoffs Considered Cost How easy/cheap is it to construct? How easy is it to view? Usability How pronounced is the effect? Effectiveness How many people can view the Multi-viewer display with stereopsis at the same time? Animation How easy is it to make an animated version of the display? Displays for the naked eye Multi-viewer is easy because people come naturally equipped Cost, usability, effectivness, and animation vary greatly SIRDS Stereo Pairs Barrier-Strip Lenticular Single Image Random Dot Stereograms (SIRDS) Commonly known as “Magic Eye” Appear to be noise -- they are! (with constrains) Guide dots (if provided) indicate propert convergence depth Only depth cue is stereo-disparity so the stereo-blind (10% of population) never see anything but noise! Remarks Notoriously difficult to view Encode little visual information Depth data is quantized (integral pixel offsets) Extremely cheap to produce (with a computer) Animation is possible (makes them easier to view as well) Stereo Image Pairs Simplest form of autostereograms Landmarks in image act a guides to aid in finding proper convergence More angular adjustment of eyes is required than in SIRDS Higher image quality at the cost of more difficult viewing Remarks Simplest to produce (darkroom, hand, software,etc.) Compelling depth effect Viewable by many people at once High-strain with extended viewing Strain limits animation Barrier Strip Displays Making viewers consciously adjust their ocular convergence is uncomfortable for some, impossible for others. Barrier strip displays use a grill of occluding elements to block view of images from either eye Viewers must be in certain locations to see effect (angle and distance are tuned) Note that barrier spacing is different than image slit spacing Remarks Encode clean stereo disparity information Comfortable for extended viewing (natural convergence point) Barriers block 50% of light going in and out, usually requres backlighting Harder to construct (ugly trig) Rigid and expensive (structure requred to maintain barrier spacing) Animation is no harder than still Commercial equipment available for medical imaging Lenticular Displays Defeat brightness problem of BS by controlling ray path with lenses instead of barriers Array of long cylindrical lenses (per pixel column) refract light to places with same distance constraint as BS, continuous angle 100% of light passes in and out, no backlighting necessary Wider field of view (limited by TIR and selfocclusion) Remarks Animation is possible with still source images using motion of viewer Able to ~reproduce lightfield More expensive/complex than BS with higher quality and less contraints Drop-in graphics libraries can turn any 3d program into a lenticular display source Displays with special viewing hardware Hardware can enable better {usability, effectiveness, multi-viewer, animation} at the cost of cost -- the normal technology vs nature tradeoff. Anaglyph Polarized Field-sequential Dual display Anaglyph Nerdy/Cool red-blue glasses Cyan, not blue! Two images overlap (like SIRDS) but are differentiated by color Filters over each eye collect light from one image but not the other Works based on intensity of light -colorblind people see them fine! Remarks Convergence is natural Crosstalk can be annoying “Color bombardment” causes strain and after-effects Strain limits long term viewing Same depth resolution/quality as raw stereo pair Small incremental cost Easy to make with (software/hand) Animation is easy Polarized Displays Approach is similar to anaglyph Polarization differentiates L-R channels Requires two polarized light projectors (instead of just a printed page) Screen must be polarization-preserving Light loss and crosstalk occur when uses tilt head Remarks The cost-wise step up from anaglyph Completely natural viewing experience No strain (unless glasses cramp your style) Ideal for theaters (IMAX), because high upfront costs and low incremental costs Field Sequential Displays Polarized projectors and screens do not make economic sense on a single-user scale Move system complexity to the glasses from the display LCD shutters over each eye control light flow from conventional display (monitor/projector) Inexpensive control box triggers shutter Several (expensive) glasses can be driven by one control box Liquid Crystal Shutter Glasses L R End of each scan-line. Remarks Convergence is natural (still) Some crosstalk can occur with lingering phosphors, slow shutters, synchronization issues Cost is proportional to the number of viewers Dual Displays Enough monkey business, just stick a monitor in front of each eye. Heavy (and expensive) headgear provides bright, immersive experience Can be combined with headphones and head tracking to modify experience based on head movement Nerd. Remarks Expensive Completely natural focus (lenses embedded in headgear) Very effective Animation is standard Only one user at a time Prices are dropping Conclusions Noooooo! My awesome comparison matrix is gone! Usability Lenticular and dual displays are best Effectiveness SIRDS and anaglyph are the worst Multi-viewer Barrier-strip and dual displays have the most constrains Animation Its always possible but strain limits application to videos